From 9a99549f5df6ef69dd1d2b509c13aaff4e431742 Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Tue, 19 May 2020 16:11:28 +0100

Subject: [PATCH 19/19] common/include: Add locale-safe ascii_strcasecmp and

 ascii_strncasecmp.

These are derived from the FreeBSD functions here:

https://github.com/freebsd/freebsd/blob/master/sys/libkern/strcasecmp.c

Thanks: Eric Blake.

(cherry picked from commit 46a29b8e91d69e812d78df53e91b526a560000fe)

---

 .gitignore                          |  1 +

 common/include/Makefile.am          |  6 +++

 common/include/ascii-ctype.h        |  6 +++

 common/include/ascii-string.h       | 77 ++++++++++++++++++++++++++++

 common/include/test-ascii-string.c  | 79 +++++++++++++++++++++++++++++

 plugins/curl/curl.c                 |  7 +--

 plugins/info/info.c                 | 17 ++++---

 plugins/nbd/nbd.c                   |  8 +--

 plugins/partitioning/partitioning.c | 10 ++--

 plugins/sh/call.c                   | 25 ++++-----

 server/main.c                       |  8 +--

 server/public.c                     | 21 ++++----

 12 files changed, 222 insertions(+), 43 deletions(-)

 create mode 100644 common/include/ascii-string.h

 create mode 100644 common/include/test-ascii-string.c

diff --git a/.gitignore b/.gitignore

index 523894b7..aa148f04 100644

--- a/.gitignore

+++ b/.gitignore

@@ -27,6 +27,7 @@ Makefile.in

 /autom4te.cache

 /common/bitmap/test-bitmap

 /common/include/test-ascii-ctype

+/common/include/test-ascii-string

 /common/include/test-byte-swapping

 /common/include/test-current-dir-name

 /common/include/test-isaligned

diff --git a/common/include/Makefile.am b/common/include/Makefile.am

index d7b0d7a8..eff71863 100644

--- a/common/include/Makefile.am

+++ b/common/include/Makefile.am

@@ -35,6 +35,7 @@ include $(top_srcdir)/common-rules.mk

 # plugins and/or filters.  They are not installed.

 EXTRA_DIST = \

 	ascii-ctype.h \

+	ascii-string.h \

 	byte-swapping.h \

 	exit-with-parent.h \

 	get-current-dir-name.h \

@@ -52,6 +53,7 @@ EXTRA_DIST = \

 TESTS = \

 	test-ascii-ctype \

+	test-ascii-string \

 	test-byte-swapping \

 	test-current-dir-name \

 	test-isaligned \

@@ -68,6 +70,10 @@ test_ascii_ctype_SOURCES = test-ascii-ctype.c ascii-ctype.h

 test_ascii_ctype_CPPFLAGS = -I$(srcdir)

 test_ascii_ctype_CFLAGS = $(WARNINGS_CFLAGS)

+test_ascii_string_SOURCES = test-ascii-string.c ascii-string.h

+test_ascii_string_CPPFLAGS = -I$(srcdir)

+test_ascii_string_CFLAGS = $(WARNINGS_CFLAGS)

+

 test_byte_swapping_SOURCES = test-byte-swapping.c byte-swapping.h

 test_byte_swapping_CPPFLAGS = -I$(srcdir)

 test_byte_swapping_CFLAGS = $(WARNINGS_CFLAGS)

diff --git a/common/include/ascii-ctype.h b/common/include/ascii-ctype.h

index 5e8bf237..a700563e 100644

--- a/common/include/ascii-ctype.h

+++ b/common/include/ascii-ctype.h

@@ -49,6 +49,9 @@

 #define ascii_isspace(c)                                                \

   ((c) == '\t' || (c) == '\n' || (c) == '\f' || (c) == '\r' || (c) == ' ')

+#define ascii_isupper(c)                        \

+  ((c) >= 'A' && (c) <= 'Z')

+

 #define ascii_isxdigit(c)                                               \

   ((c) == '0' || (c) == '1' || (c) == '2' || (c) == '3' || (c) == '4' || \

    (c) == '5' || (c) == '6' || (c) == '7' || (c) == '8' || (c) == '9' || \

@@ -57,4 +60,7 @@

    (c) == 'A' || (c) == 'B' || (c) == 'C' ||                            \

    (c) == 'D' || (c) == 'E' || (c) == 'F')

+#define ascii_tolower(c)                        \

+  (ascii_isupper ((c)) ? (c) - 'A' + 'a' : (c))

+

 #endif /* NBDKIT_ASCII_CTYPE_H */

diff --git a/common/include/ascii-string.h b/common/include/ascii-string.h

new file mode 100644

index 00000000..0a60d5f4

--- /dev/null

+++ b/common/include/ascii-string.h

@@ -0,0 +1,77 @@

+/* nbdkit

+ * Copyright (C) 2013-2020 Red Hat Inc.

+ *

+ * Redistribution and use in source and binary forms, with or without

+ * modification, are permitted provided that the following conditions are

+ * met:

+ *

+ * * Redistributions of source code must retain the above copyright

+ * notice, this list of conditions and the following disclaimer.

+ *

+ * * Redistributions in binary form must reproduce the above copyright

+ * notice, this list of conditions and the following disclaimer in the

+ * documentation and/or other materials provided with the distribution.

+ *

+ * * Neither the name of Red Hat nor the names of its contributors may be

+ * used to endorse or promote products derived from this software without

+ * specific prior written permission.

+ *

+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND

+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR

+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT

+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

+ * SUCH DAMAGE.

+ */

+

+/* Case insensitive string comparison functions (like strcasecmp,

+ * strncasecmp) which work correctly in any locale.  They can only be

+ * used for comparison when one or both strings is 7 bit ASCII.

+ */

+

+#ifndef NBDKIT_ASCII_STRING_H

+#define NBDKIT_ASCII_STRING_H

+

+#include "ascii-ctype.h"

+

+static inline int

+ascii_strcasecmp (const char *s1, const char *s2)

+{

+  const unsigned char *us1 = (const unsigned char *)s1;

+  const unsigned char *us2 = (const unsigned char *)s2;

+

+  while (ascii_tolower (*us1) == ascii_tolower (*us2)) {

+    if (*us1++ == '\0')

+      return 0;

+    us2++;

+  }

+

+  return ascii_tolower (*us1) - ascii_tolower (*us2);

+}

+

+static inline int

+ascii_strncasecmp (const char *s1, const char *s2, size_t n)

+{

+  if (n != 0) {

+    const unsigned char *us1 = (const unsigned char *)s1;

+    const unsigned char *us2 = (const unsigned char *)s2;

+

+    do {

+      if (ascii_tolower (*us1) != ascii_tolower (*us2))

+        return ascii_tolower (*us1) - ascii_tolower (*us2);

+      if (*us1++ == '\0')

+        break;

+      us2++;

+    } while (--n != 0);

+  }

+

+  return 0;

+}

+

+#endif /* NBDKIT_ASCII_STRING_H */

diff --git a/common/include/test-ascii-string.c b/common/include/test-ascii-string.c

new file mode 100644

index 00000000..0fa4a483

--- /dev/null

+++ b/common/include/test-ascii-string.c

@@ -0,0 +1,79 @@

+/* nbdkit

+ * Copyright (C) 2020 Red Hat Inc.

+ *

+ * Redistribution and use in source and binary forms, with or without

+ * modification, are permitted provided that the following conditions are

+ * met:

+ *

+ * * Redistributions of source code must retain the above copyright

+ * notice, this list of conditions and the following disclaimer.

+ *

+ * * Redistributions in binary form must reproduce the above copyright

+ * notice, this list of conditions and the following disclaimer in the

+ * documentation and/or other materials provided with the distribution.

+ *

+ * * Neither the name of Red Hat nor the names of its contributors may be

+ * used to endorse or promote products derived from this software without

+ * specific prior written permission.

+ *

+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND

+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR

+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT

+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

+ * SUCH DAMAGE.

+ */

+

+#include <config.h>

+

+#include <stdio.h>

+#include <stdlib.h>

+#include <assert.h>

+

+#include "ascii-string.h"

+

+int

+main (void)

+{

+  assert (ascii_strcasecmp ("", "") == 0);

+  assert (ascii_strcasecmp ("a", "a") == 0);

+  assert (ascii_strcasecmp ("abc", "abc") == 0);

+  assert (ascii_strcasecmp ("a", "b") < 0);

+  assert (ascii_strcasecmp ("b", "a") > 0);

+  assert (ascii_strcasecmp ("aa", "a") > 0);

+

+  /* Second string contains Turkish dotless lowercase letter 覺. */

+  assert (ascii_strcasecmp ("hi", "h覺") != 0);

+

+  /* Check that we got our rounding behaviour correct. */

+  assert (ascii_strcasecmp ("\x1", "\x7f") < 0);

+  assert (ascii_strcasecmp ("\x1", "\x80") < 0);

+  assert (ascii_strcasecmp ("\x1", "\x81") < 0);

+  assert (ascii_strcasecmp ("\x1", "\xff") < 0);

+

+  assert (ascii_strncasecmp ("", "", 0) == 0);

+  assert (ascii_strncasecmp ("a", "a", 1) == 0);

+  assert (ascii_strncasecmp ("abc", "abc", 3) == 0);

+  assert (ascii_strncasecmp ("abc", "def", 0) == 0);

+  assert (ascii_strncasecmp ("abc", "abd", 2) == 0);

+  assert (ascii_strncasecmp ("a", "b", 1) < 0);

+  assert (ascii_strncasecmp ("b", "a", 1) > 0);

+  assert (ascii_strncasecmp ("aa", "a", 2) > 0);

+  assert (ascii_strncasecmp ("aa", "a", 100) > 0);

+

+  assert (ascii_strncasecmp ("hi", "h覺", 1) == 0);

+  assert (ascii_strncasecmp ("hi", "h覺", 2) != 0);

+

+  assert (ascii_strncasecmp ("\x1", "\x7f", 1) < 0);

+  assert (ascii_strncasecmp ("\x1", "\x80", 1) < 0);

+  assert (ascii_strncasecmp ("\x1", "\x81", 1) < 0);

+  assert (ascii_strncasecmp ("\x1", "\xff", 1) < 0);

+

+  exit (EXIT_SUCCESS);

+}

diff --git a/plugins/curl/curl.c b/plugins/curl/curl.c

index ac30cbdd..00f0628a 100644

--- a/plugins/curl/curl.c

+++ b/plugins/curl/curl.c

@@ -58,6 +58,7 @@

 #include "cleanup.h"

 #include "ascii-ctype.h"

+#include "ascii-string.h"

 static const char *url = NULL;

 static const char *user = NULL;

@@ -419,8 +420,8 @@ curl_open (int readonly)

 #endif

   nbdkit_debug ("content length: %" PRIi64, h->exportsize);

-  if (strncasecmp (url, "http://", strlen ("http://")) == 0 ||

-      strncasecmp (url, "https://", strlen ("https://")) == 0) {

+  if (ascii_strncasecmp (url, "http://", strlen ("http://")) == 0 ||

+      ascii_strncasecmp (url, "https://", strlen ("https://")) == 0) {

     if (!h->accept_range) {

       nbdkit_error ("server does not support 'range' (byte range) requests");

       goto err;

@@ -504,7 +505,7 @@ header_cb (void *ptr, size_t size, size_t nmemb, void *opaque)

   const char *bytes = "bytes";

   if (realsize >= strlen (accept_ranges) &&

-      strncasecmp (header, accept_ranges, strlen (accept_ranges)) == 0) {

+      ascii_strncasecmp (header, accept_ranges, strlen (accept_ranges)) == 0) {

     const char *p = strchr (header, ':') + 1;

     /* Skip whitespace between the header name and value. */

diff --git a/plugins/info/info.c b/plugins/info/info.c

index 329a3684..e04d672b 100644

--- a/plugins/info/info.c

+++ b/plugins/info/info.c

@@ -49,6 +49,7 @@

 #include <nbdkit-plugin.h>

+#include "ascii-string.h"

 #include "byte-swapping.h"

 #include "tvdiff.h"

@@ -76,12 +77,12 @@ static int

 info_config (const char *key, const char *value)

 {

   if (strcmp (key, "mode") == 0) {

-    if (strcasecmp (value, "exportname") == 0 ||

-        strcasecmp (value, "export-name") == 0) {

+    if (ascii_strcasecmp (value, "exportname") == 0 ||

+        ascii_strcasecmp (value, "export-name") == 0) {

       mode = MODE_EXPORTNAME;

     }

-    else if (strcasecmp (value, "base64exportname") == 0 ||

-             strcasecmp (value, "base64-export-name") == 0) {

+    else if (ascii_strcasecmp (value, "base64exportname") == 0 ||

+             ascii_strcasecmp (value, "base64-export-name") == 0) {

 #ifdef HAVE_BASE64

       mode = MODE_BASE64EXPORTNAME;

 #else

@@ -89,13 +90,13 @@ info_config (const char *key, const char *value)

       return -1;

 #endif

     }

-    else if (strcasecmp (value, "address") == 0)

+    else if (ascii_strcasecmp (value, "address") == 0)

       mode = MODE_ADDRESS;

-    else if (strcasecmp (value, "time") == 0)

+    else if (ascii_strcasecmp (value, "time") == 0)

       mode = MODE_TIME;

-    else if (strcasecmp (value, "uptime") == 0)

+    else if (ascii_strcasecmp (value, "uptime") == 0)

       mode = MODE_UPTIME;

-    else if (strcasecmp (value, "conntime") == 0)

+    else if (ascii_strcasecmp (value, "conntime") == 0)

       mode = MODE_CONNTIME;

     else {

       nbdkit_error ("unknown mode: '%s'", value);

diff --git a/plugins/nbd/nbd.c b/plugins/nbd/nbd.c

index d020beec..980ce8ec 100644

--- a/plugins/nbd/nbd.c

+++ b/plugins/nbd/nbd.c

@@ -52,6 +52,8 @@

 #define NBDKIT_API_VERSION 2

 #include <nbdkit-plugin.h>

+

+#include "ascii-string.h"

 #include "byte-swapping.h"

 #include "cleanup.h"

 #include "utils.h"

@@ -152,9 +154,9 @@ nbdplug_config (const char *key, const char *value)

     shared = r;

   }

   else if (strcmp (key, "tls") == 0) {

-    if (strcasecmp (value, "require") == 0 ||

-        strcasecmp (value, "required") == 0 ||

-        strcasecmp (value, "force") == 0)

+    if (ascii_strcasecmp (value, "require") == 0 ||

+        ascii_strcasecmp (value, "required") == 0 ||

+        ascii_strcasecmp (value, "force") == 0)

       tls = LIBNBD_TLS_REQUIRE;

     else {

       r = nbdkit_parse_bool (value);

diff --git a/plugins/partitioning/partitioning.c b/plugins/partitioning/partitioning.c

index 6e426b93..e35764dc 100644

--- a/plugins/partitioning/partitioning.c

+++ b/plugins/partitioning/partitioning.c

@@ -48,6 +48,7 @@

 #include <nbdkit-plugin.h>

+#include "ascii-string.h"

 #include "byte-swapping.h"

 #include "isaligned.h"

 #include "iszero.h"

@@ -176,9 +177,10 @@ partitioning_config (const char *key, const char *value)

     nr_files++;

   }

   else if (strcmp (key, "partition-type") == 0) {

-    if (strcasecmp (value, "mbr") == 0 || strcasecmp (value, "dos") == 0)

+    if (ascii_strcasecmp (value, "mbr") == 0 ||

+        ascii_strcasecmp (value, "dos") == 0)

       parttype = PARTTYPE_MBR;

-    else if (strcasecmp (value, "gpt") == 0)

+    else if (ascii_strcasecmp (value, "gpt") == 0)

       parttype = PARTTYPE_GPT;

     else {

       nbdkit_error ("unknown partition-type: %s", value);

@@ -209,13 +211,13 @@ partitioning_config (const char *key, const char *value)

     alignment = r;

   }

   else if (strcmp (key, "mbr-id") == 0) {

-    if (strcasecmp (value, "default") == 0)

+    if (ascii_strcasecmp (value, "default") == 0)

       mbr_id = DEFAULT_MBR_ID;

     else if (nbdkit_parse_uint8_t ("mbr-id", value, &mbr_id) == -1)

       return -1;

   }

   else if (strcmp (key, "type-guid") == 0) {

-    if (strcasecmp (value, "default") == 0)

+    if (ascii_strcasecmp (value, "default") == 0)

       parse_guid (DEFAULT_TYPE_GUID, type_guid);

     else if (parse_guid (value, type_guid) == -1) {

       nbdkit_error ("could not validate GUID: %s", value);

diff --git a/plugins/sh/call.c b/plugins/sh/call.c

index ba9f055f..554e2f78 100644

--- a/plugins/sh/call.c

+++ b/plugins/sh/call.c

@@ -48,6 +48,7 @@

 #include <nbdkit-plugin.h>

 #include "ascii-ctype.h"

+#include "ascii-string.h"

 #include "cleanup.h"

 #include "utils.h"

@@ -332,48 +333,48 @@ handle_script_error (const char *argv0, char *ebuf, size_t len)

   }

   /* Recognize the errno values that match NBD protocol errors */

-  if (strncasecmp (ebuf, "EPERM", 5) == 0) {

+  if (ascii_strncasecmp (ebuf, "EPERM", 5) == 0) {

     err = EPERM;

     skip = 5;

   }

-  else if (strncasecmp (ebuf, "EIO", 3) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EIO", 3) == 0) {

     err = EIO;

     skip = 3;

   }

-  else if (strncasecmp (ebuf, "ENOMEM", 6) == 0) {

+  else if (ascii_strncasecmp (ebuf, "ENOMEM", 6) == 0) {

     err = ENOMEM;

     skip = 6;

   }

-  else if (strncasecmp (ebuf, "EINVAL", 6) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EINVAL", 6) == 0) {

     err = EINVAL;

     skip = 6;

   }

-  else if (strncasecmp (ebuf, "ENOSPC", 6) == 0) {

+  else if (ascii_strncasecmp (ebuf, "ENOSPC", 6) == 0) {

     err = ENOSPC;

     skip = 6;

   }

-  else if (strncasecmp (ebuf, "EOVERFLOW", 9) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EOVERFLOW", 9) == 0) {

     err = EOVERFLOW;

     skip = 9;

   }

-  else if (strncasecmp (ebuf, "ESHUTDOWN", 9) == 0) {

+  else if (ascii_strncasecmp (ebuf, "ESHUTDOWN", 9) == 0) {

     err = ESHUTDOWN;

     skip = 9;

   }

-  else if (strncasecmp (ebuf, "ENOTSUP", 7) == 0) {

+  else if (ascii_strncasecmp (ebuf, "ENOTSUP", 7) == 0) {

     err = ENOTSUP;

     skip = 7;

   }

-  else if (strncasecmp (ebuf, "EOPNOTSUPP", 10) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EOPNOTSUPP", 10) == 0) {

     err = EOPNOTSUPP;

     skip = 10;

   }

   /* Other errno values that server/protocol.c treats specially */

-  else if (strncasecmp (ebuf, "EROFS", 5) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EROFS", 5) == 0) {

     err = EROFS;

     skip = 5;

   }

-  else if (strncasecmp (ebuf, "EDQUOT", 6) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EDQUOT", 6) == 0) {

 #ifdef EDQUOT

     err = EDQUOT;

 #else

@@ -381,7 +382,7 @@ handle_script_error (const char *argv0, char *ebuf, size_t len)

 #endif

     skip = 6;

   }

-  else if (strncasecmp (ebuf, "EFBIG", 5) == 0) {

+  else if (ascii_strncasecmp (ebuf, "EFBIG", 5) == 0) {

     err = EFBIG;

     skip = 5;

   }

diff --git a/server/main.c b/server/main.c

index 11ba1e6d..08116d74 100644

--- a/server/main.c

+++ b/server/main.c

@@ -55,6 +55,8 @@

 #include <dlfcn.h>

+#include "ascii-string.h"

+

 #include "internal.h"

 #include "nbd-protocol.h"

 #include "options.h"

@@ -282,9 +284,9 @@ main (int argc, char *argv[])

     case TLS_OPTION:

       tls_set_on_cli = true;

-      if (strcasecmp (optarg, "require") == 0 ||

-          strcasecmp (optarg, "required") == 0 ||

-          strcasecmp (optarg, "force") == 0)

+      if (ascii_strcasecmp (optarg, "require") == 0 ||

+          ascii_strcasecmp (optarg, "required") == 0 ||

+          ascii_strcasecmp (optarg, "force") == 0)

         tls = 2;

       else {

         tls = nbdkit_parse_bool (optarg);

diff --git a/server/public.c b/server/public.c

index 98b78482..919f082d 100644

--- a/server/public.c

+++ b/server/public.c

@@ -52,6 +52,7 @@

 #include <sys/socket.h>

 #include "ascii-ctype.h"

+#include "ascii-string.h"

 #include "get-current-dir-name.h"

 #include "internal.h"

@@ -385,19 +386,19 @@ int

 nbdkit_parse_bool (const char *str)

 {

   if (!strcmp (str, "1") ||

-      !strcasecmp (str, "true") ||

-      !strcasecmp (str, "t") ||

-      !strcasecmp (str, "yes") ||

-      !strcasecmp (str, "y") ||

-      !strcasecmp (str, "on"))

+      !ascii_strcasecmp (str, "true") ||

+      !ascii_strcasecmp (str, "t") ||

+      !ascii_strcasecmp (str, "yes") ||

+      !ascii_strcasecmp (str, "y") ||

+      !ascii_strcasecmp (str, "on"))

     return 1;

   if (!strcmp (str, "0") ||

-      !strcasecmp (str, "false") ||

-      !strcasecmp (str, "f") ||

-      !strcasecmp (str, "no") ||

-      !strcasecmp (str, "n") ||

-      !strcasecmp (str, "off"))

+      !ascii_strcasecmp (str, "false") ||

+      !ascii_strcasecmp (str, "f") ||

+      !ascii_strcasecmp (str, "no") ||

+      !ascii_strcasecmp (str, "n") ||

+      !ascii_strcasecmp (str, "off"))

     return 0;

   nbdkit_error ("could not decipher boolean (%s)", str);

-- 

2.18.2